I have used 2.7 to 5.5 grains of Trailboss and 2.8 to 4.2 grains of Bullseye with that bullet. 3.5 grains Trailboss is very clean and accurate and will cycle most 1911's with the standard spring. 3.6 grains Bullseye is good as well, but you might have to go to a lighter spring, like 10-LB. The 200 LSWC Bullseye No. 1 is a better bullet for me in a 1911 with the same charges. A little more accurate and feeds a little better than the RNFP. I am shooting a Colt Special Combat Government and a Colt Model 70 government.